Integral quench furnace and transfer mechanism

ABSTRACT

An integral quench furnace system and transfer mechanism for removing a heat treated charge from the furnace chamber into the quench media and onto an unloading platform. The transfer mechanism includes a forked loading cart mounted on the quench chamber A-frame for movement into the furnace and onto the unloading platform through a hydraulic motor driven chain and sprocket arrangement.

United States Patent Reber et al.

[54] INTEGRAL QUENCH FURNACE AND TRANSFER MECHANISM [72] Inventors:Russell H. Reber, Orange; Harold E.

Mescher, Pico Rivera, both of Calif.

Pacific Scientific Company, City of Commerce, Calif.

[22] Filed: Aug. 25, 1969 [21] Appl.N0.: 852,671

[73] Assignee:

[52] U.S.Cl. ..266/4A,148/153,214/18R,

214/26 51 im. Cl. ..C21d1/66 [58] Field ofSearch ..148/153, 155; 214/18R, 23-26, 214/32; 266/4 R, 4 A, 4 B, 6 R

[56] References Cited UNITED STATES PATENTS 1,840,327 1/1932 Paulsen..214/26 1,848,898 3/1932 McFarland ..2l4/26 [451 May 2, 1972 2,681,1366/1954 lpsen ..266/4 R 2,747,855 5/1956 lpsen ..266/4 R 2,965,36912/1960 Acker et al ..266/4 R 3,381,947 5/1968 Beggs ..266/4 R 3,410,54711/1968 Bielefeldt... .....266/5 R 3,441,452 4/1969 Westeren ..266/4 RFOREIGN PATENTS OR APPLICATIONS 987,910 8/1951 France ..266/4 R PrimaryExaminer-Gerald A. Dost Atrorney-Fowler, Knobbe & Martens [57] ABSTRACTAn integral quench furnace system and transfer mechanism for removing aheat treated charge from the furnace chamber into the quench media andonto an unloading platform. The transfer mechanism includes a forkedloading cart mounted on the quench chamber A-frame for movement into thefurnace and onto the unloading platform through a hydraulic motor drivenchain and sprocket arrangement,

22 Claims, 13 Drawing Figures Patented May 2, 1972 i0 Sheets-Sheet lINVENTORS.

EL/iSEZL H E5551? M45040 5. M53045? FOWL 5/6 (M0555 M42 TEN5 10Sheets-Sheet .FZ G Z INVENTORS. 0555 H. 2655? 144E040 6'. 4455045 BYPOM/L 5 44/0555 MflETE/VS Patented May 2, 1972 i0 Sheets-Sheet l5INVENTOR5. 2055624 A! E5556 #42040 5. MESKHEE BY ran 452, K/V055E ,4WMFTzF/VS Patented May 2, 1972 10 Sheets-Sheet 4 INVENTORfi. 60.516224 4E5552 ran 4 6, K/VOBBE a M4275;

Patented May 2, 1972 3,659,831

l0 Sheets-Sheet 5 INVENTORS. FUSSELL h. @5545? Patented May 2, 1972 10Sheets-Sheet 6 INVENTORS. 2055621. HEEBEE A/flEOLD E M55095? BY K/V055EFOWL 2,

a Ame rlsws Patented May 2, 1972 3,659,831

10 Sheets-Sheet 7 EGQ INVENTORS.

EUSKSZZL H 5552 mf/QEOLD E. MESffi/EF Patented May 2, 1972 10Sheets-Sheet 8 fi e. /0.

INVENTORS. H. 1655678 05562 L #41701 0 E. M556 47' TOIQNE K61 INTEGRALQUENCH FURNACE AND TRANSFER MECHANISM This invention is directed tometallurgical heat treating equipment and more specifically to atransfer mechanism for use with integral quench vacuum or atmospherefurnaces.

Prior art heat treating furnaces which combine a quench chamber andfurnace heating chamber are generally incapable of rapidly transferringthe charge being heat treated from the furnace chamber into the quenchmedia without dropping the charge into the quench tank. Suchuncontrolled movement of the charge may cause distortion of theworkpiece and usually cannot be tolerated. Additionally the priorequipment generally leaves a portion of the transfer mechanism in thefurnace during the heat treating cycle and then immerses this sameportion of the mechanism into the quench fluids. Usually no effectivemeans is provided for cleaning the quench fluids from this portion ofthe transfer mechanism before it is reinserted into the furnace. Thisportion, whether it be support rollers, pallets or other equipment, dueto the continuous thermal stress cycling and exposure to the hightemperature of the furnace chamber may eventually contaminate the heattreating furnace or become corroded or cracked. Any time that extraneousmaterials, such as portions of the transfer mechanism, are left in thefurnace chamber, the danger of outdiffusion and contamination of theatmosphere or the charge is present. Even small amounts of contaminationcannot be tolerated for high quality heat treating work such as withvacuum or atmosphere furnaces.

Additionally, in the prior art furnaces it sometimes is necessary toslide the charge on the refractory hearths while at temperature. Thismay cause defacing of the hearths and the charge or introduce distortingstresses into the charge metals.

Another difficulty with integral quench vacuum or atmosphere furnacespresently available is that the furnace chamber and the quench chamberare generally separated by a hingemounted door which swings into thequench chamber. Such doors are provided since they must preventradiation losses from within the furnace insulation lining and seal theheat treating chamber from the partial pressure of the quenchingchamber. Because the entrance to the furnace housing is not flush withthe entrance to the furnace chamber, the radiation seal protrudes beyondthe vacuum seal. Consequently, it has been thought that the hinged doorswere the only type usable. Such swing-in doors consume a large amount ofspace when opened causing unnecessary lengthening of the quench chamber.

In integral quench vacuum furnaces the transfer mechanism fortransferring the heat treated charge into the quenching media must becapable of rapidly moving into the heat treating chamber once the heattreat is completed and the door has been opened, picking up the charge,and returning the charge into position over the quenching media. Thereturn stroke of the transfer mechanism, however, must not be so rapidthat the heated charge is jarred, slid or distorted by jerking movementor quick stops. i

To be completely acceptable, the transfer mechanism must also provide aneffective means for removing the charge from the quenching media and thequench chamber onto an unloading platform where any portion of thetransfer mechanism which may enter the furnace chamber can be wipedclean of the quenching fluids after the quench has been completed. Thisrequires some precise manner of alignment of the transfer mechanism withthe unloading platform which enables the charge to be correctlypositioned on the unloading platform after removal.

From the requirements for the transfer mechanism, it is clear that themechanism must be capable of both horizontal and vertical translation.The vertical translation must be accurately controlled in a steppedfashion so that the transfer mechanism can be stepped vertically toenter the furnace chamber beneath the charge and be raised to pick upthe charge. During unloading, however, the transfer mechanism must bealigned with the unloading platform at a level which most convenientlyis even with the level of the transfer mechanism after the charge hasbeen picked up. This enables the mechanism to transfer directly from theheat treating chamber onto the unloading platform omitting the quench ifdesired. A third vertical position that the transfer mechanism mustassume is a position which places the heat treated charge within thequenching media.

This invention is basically an integral quench furnace system and atransfer mechanism which is designed for use in conjunction withintegral quench metallurgical heat treating furnaces, i.e., furnaceswhich are divided into a quenching chamber and a heating or holding attemperature chamber. The transfer mechanism comprises a loading cartwhich is horizontally translatable and a vertically translatable supportframe which mounts and supports the loading cart. The support frame thusdetermines the vertical position from which the loading cart willtranslate horizontally. The heat treating equipment and transfermechanism also includes a horizontally translatable alignment andunloading frame. Reversible means are provided for driving the loadingcart and the alignment frame at different speeds in a loading and areverse direction so that the loading cart can rapidly move from thequench chamber enabling a portion of it to enter the furnace chamber andretrieve the heat treated charge without having the alignment frameenter the furnace chamber.

The integral quench furnace system of this invention further includescontrol means for accelerating and then decelerating the loading cart asit retrieves the heat treated charge from the furnace chamber andreturns it to position over the quenching media in the quench chamber.Actuatable pistons are provided for vertically positioning the supportframe for the leading cart to enable the loading cart to be translatedhorizontally from various vertical levels to enter the furnace chamber,lift the heat treated charge, and immerse the charge in the quenchingmedia.

After the quenching has been completed, the loading cart may bevertically returned to its initial or home" position within the quenchchamber and both the loading cart and the alignment and unloading framemay be translated horizontally away from the furnace toward an unloadingstation. During this translation the loading cart is disengaged from itsdrive mechanism until alignment with the unloading platform has beenachieved by the alignment frame. Means are then provided on theunloading platform for engaging the loading cart and translating theloading cart horizontally out of the quench chamber onto an unloadingplatform where the charge can be removed and the portions of the cartwhich enter the high temperature chamber can easily be wiped clean.

One feature of the apparatus of this invention is that a rapidtranslation of a heat treated charge from the furnace into the quenchingmedia can be obtained without distortion, sliding, or uncontrolledmovement of the heat treated charge.

Another feature of the heat treating furnace system of this invention isthat the heat treatment and quenching of the heat treated charge can beaccomplished rapidly in a controlled manner within a closed system.

Another feature of the apparatus of this invention is that it is notnecessary to leave any portion of the transfer mechanism in the heattreating chamber during heat treatment of the charge so thatcontaminants are not thereby introduced into the heat treating chamber.

Yet another feature of the heat treating furnace and transfer mechanismof this invention is that the apparatus can be readily automated forheat treating a series of charges in a programmed heat treating,quenching and removal cycle.

Still another feature of the heat treating furnace of this invention isthat the furnace chamber is separated from the quench chamber by meansof vertically sliding gates which do not require elongation of thequench chamber to maintain a vacuum within the furnace chamber and topermit automatic translation of the heat treated charge from the furnacechamber into the quench chamber.

Yet another feature of the heat treating equipment of this invention isthat the charge transfer mechanism lifts the charge off of the furnacehearth and accelerates and then decelerates in transferring the chargeto the quench chamber.

Still another feature of the heat treating equipment of this inventionis that atmosphere facing seals are eliminated by the use of hydraulicactuators to operate the furnace mechanism.

These and other features of the heat treating furnace and transfermechanism of this invention will become more readily apparent from aconsideration of the following detailed description and the appendedclaims when taken in conjunction with the attached drawings which may bebriefly described as follows:

FIG. 1 is a partially sectioned view taken vertically through a planesubstantially parallel to the longitudinal axis of an integral quenchfurnace system constructed in accordance with this invention;

FIG. 2 is an enlarged partially sectioned view through a planesubstantially parallel to the longitudinal axis of the quenching chambershowing a transfer mechanism constructed in accordance with thisinvention;

FIG. 3 is a perspective view of an A-frame charge support member fromthe quench chamber, a forked loading cart, and an alignment frame of atransfer mechanism constructed in accordance with this invention;

FIG. 4 is an enlarged transverse sectional view taken substantiallyalong lines 4-4 of FIG. 2;

FIG. 5 is a somewhat diagrammatic view of the drive system for atransfer mechanism as shown in FIG. 3;

FIG. 6 is a horizontal sectional view taken along the longitudinal axisof the furnace system showing the relationship between the hearthmembers and the transfer mechanism;

FIG. 7 is a partial sectional view taken through a vertical planesubstantially parallel to the longitudinal axis of the system showingthe furnace chamber and the quench chamber showing a transfer mechanismconstructed in accordance with this invention in the charge pick upposition;

FIG. 8 is a transverse sectional view through the quench chamber showinga transfer mechanism constructed in accordance with this invention withthe support A-frame in the fully upward position;

FIG. 9 is an enlarged view of the vertical positioning mechanism for thetransfer mechanism shown in FIG. 8 showing the pistons position when theA-frame support is in position for the loading cart to enter the furnacechamber;

FIG. 10 is an enlarged partially sectioned view of the drive chain andloading cart engaging mechanism used with the transfer mechanismconstructed in accordance with this invention;

FIG. 11 is an enlarged segmental view of the alignment members for thetransfer mechanism and loading platform constructed in accordance withthis invention;

FIG. 12 is a vertical sectional view taken through a plane substantiallyparallel to the longitudinal axis of the integral quench furnace showingthe transfer mechanism as the loading cart begins to be driven onto theunloading platform in accordance with the mechanism of this invention;and

FIG. 13 is a time sequencing diagram for operation of an integral quenchfurnace having a transfer mechanism constructed in accordance with thisinvention.

Referring now to FIG. I, the basic construction of the integral quenchvacuum or atmosphere furnace with the transfer mechanism of thisinvention can be seen in cross-section. While the furnace can readily beadapted for vacuum or selected atmosphere heat treatment, it will bediscussed for use with vacuum alone. The integral quench furnace systemcomprises a furnace chamber 10 and an integrally attached, horizontallydisposed quench chamber 12. A horizontally and vertically translatablefork-type charge loading platform 14 is positioned adjacent the entrancedoor to the furnace chamber and an unloading platform 16 is spaced nearthe discharge door from the quench chamber 12 in fixed relationship withthe quench chamber.

The furnace chamber includes a refractory insulating lining 20, a set oflongitudinally extending elevated hearth members 22 (see FIG. 6), avertically slideable furnace entrance door 24 and a vertically slideablefurnace exit door 26. The doors 24 and 26 are juxtaposed in sealingrelationship with the entrance and exit to the furnace chamber 10 bymeans of resilient sealing members 25 and 27 mounted in appropriategrooves in the doors so as to slide into sealing relationship with theentrance and exit framework, respectively. The doors 24 and 26 includeretractable refractory radiation shields or plugs 27 and 28 which areextendible by means of hydraulic piston actuators 29 and 30 into closingrelationship with the refractory lining of the furnace as shown inFIG. 1. The actuators 29 and 30 in the piston extended position maintainplugs 27 and 28 in contact with the lining 20. The shields and thefurnace lining, for example, may be graphite or other refractorymaterial.

A vacuum tight compartment 31 is integrally connected to the furnacechamber 10 and the quench chamber 12 for receiving the door 26 when itis opened.

The hearth, as best shown in FIG. 6, actually in the preferredembodiment comprises four refractory hearth members 22. These hearthmembers 22 are constructed of a suitable metal having a refractorymaterial liner and mounted on vertically extending support bars 32 abovethe radiant heaters of the furnace (not shown). Any conventional radiantheating units may be used. For example these may be the tubularresistant heating elements disclosed in Us. Pat. No. 3,368,022 toMescher et a]. or other similar resistant type heating elements.

The heat treating chamber 10 includes a vacuum tight, cold wall housing34. The housing 34 includes the entrance and exit frames 36 and 38,respectively, which sealingly engage the resilient seals 25 and 27 forproviding an airtight seal between the vertically slideable doors 24 and26 and the furnace 10. A vacuum pump 39 with appropriate exhaust conduitis pro vided for evacuating the furnace 10. Conventional cooling fans(not shown) may be provided intermediate the housing 34 and insulatedlining 20. Additionally, an agitator 37 may be provided within thequench chamber 12 (see FIG. 8).

The transfer mechanism 40 is mounted within the quench chamber 12 andbasically comprises a vertically translatable quench chamber A-framecharge support member 41 which carries a horizontally translatableforked charge loading cart 42 and a horizontally translatable guide andalignment frame 43 (see FIG. 3).

The vertically translatable A-frame charge support member 41, as bestshown in FIGS. 2, 3 and 4, includes a pair of Iongitudinally extendingrectangular side base plates 44 which are each connected at about theircenters to a vertically extending angle iron support beam 46. Thevertical support beams 46 are connected to each other by a transverselyextending support beam 48 which has a flat upper surface 49. Foursupport struts 50 are connected to the upper end of the vertical supportbeams 46 and are inclined downwardly where they are attached to theopposite end portions of the side base plates 44 to form the typicalA-frame configuration. The entire A-frame 41 may be made from heavy gageangle irons and plate stock joined by welding, bolting or any otherconventional manner.

The vertical support beams 46 are provided in their outer channels withtwo pairs of longitudinally spaced, peripherally grooved rollers 52 neartheir upper and lower ends for riding on vertical guide bars 54 (seeFIG. 6) within the quench chamber 12.

With continued reference to FIGS. 3 and 4, the horizontally extendingside plates 44 of the A-frame charge support member 41 on their inwardlyfacing surfaces near their upper and lower edges are provided with aseries of longitudinally spaced, rotatably mounted, alignment frameguide rollers or wheels 56 and 60 which are peripherally grooved. Theupper guide rollers 56, as shown in FIG. 4, are mounted for rotation onbushings 57 which are bolted or otherwise affixed to the side plates 44of the A-frame. Some of the lower guide rollers 60 are mounted onbushings 61 which pass over cylindrical shafts 62, 64 and 66 shown inFIG. 2. The remainder of the lower rollers 60 are bolted to the sideplates 44 in a similar manner to rollers 56 so that they are rotatable.As shown in FIGS. 2. 3 and 4 there are five upper rollers 56 which arevertically spaced from five lower rollers 60. Both plates 44 areprovided with these rollers. The exact manner in which the rollers aremounted may be varied as long as they can rotate.

The horizontally translatable guide and alignment frame 43 comprises apair of substantially rectangular, transversely spaced, substantiallyparallel side guide plates 58 mounted between the upper and lowergrooved wheels 56 and 60 on the A-frame side plates 44 for horizontalmovement thereover. Each side guide plate 58 is a flat sheet of metalwhich is basically longitudinally coextensive with the side 44 of the A-frame of the transfer mechanism on which it is mounted. As best shown inFIG. 5, the side guide plates 58 are juxtaposed between upper and lowerguide wheels 56 and 60 respectively so that the side guide plates 58 canbe translated horizontally into and out of the A-frame. Each of the sideguide plates 58 at about their centers mount a cylindrical,longitudinally extending guide rail 59. The rails 59 may be attached tothe alignment frame side guide plates 58 by any conventional means suchas by welding.

With continued reference to FIGS. 3, 4, 5 and 6, it will be seen thatthe forked loading cart 42 basically comprises three longitudinallyextending, transversely spaced, cylindrical, barlike prongs or liftmembers 90, 92 and 94. These prongs are connected to three transverselyextending support plates 96, 98 and 100 (see FIGS. 3 and 6), which areconnected to a pair of longitudinally extending side plates 102 and 104to form the support structure for the prongs 9094. The support plate 100on its surface facing the unloading platform 16 fixedly mounts a pair ofdepending fingers 101. A pair of depending stop brackets 103 are mountedon support plates 98 and 100 to depend in transversely spacedrelationship therefrom. The fingers 101 and brackets 103 may be boltedas shown in FIGS. 3 and 10.

Each of the side plates 102 and 104 carry two pairs of vertically spacedwheels or rollers 106 (see FIG. 4) which have concave peripheral groovestherein for riding on the guide rails 59 on the side guide plates 58.The rollers 106 are mounted for rotation on bushings 107 which arebolted to the side plates 58 as shown in FIG. 4. Alternatively theserollers may be journaled in the side plates or mounted in any othermanner for facilitating movement of the forked loading cart 41 on therails 59. In other words, the rollers 106 are mounted in a mannersimilar to the rollers 56 and 60 on the side guide plates 58. Therollers 106 not only permit easy horizontal movement of the forkedloading cart 42, but also prevent pivotal movement of the loading cartwhen the cart is extended into the furnace chamber and picks up a loadon the prongs 90, 92 and 94 (see FIG. 7). The rollers 106 must, thus, beattached to the side plates 102 and 104 of the forked loading cart 42 bybolts which are sufficiently strong to resist the shear force momentumofa load on the prongs 90, 92 and 94.

With continued reference to FIG. 3 and with reference to FIG. 5, it willbe seen that the drive mechanism for the transfer mechanism 40 comprisesa series of continuous chains and sprockets driven by a hydraulic motor110. The motor 110 is coupled to a linear operator motor speed controlvalve 112 which regulates the motor speed by controlling the flow volumeof hydraulic fluid into the motor through conventional hydrauliccircuitry. The drive shaft 113 of the motor 110 is rotatably connectedto a sprocket 114. The sprocket 114 operatively engages a mechanismdrive chain 116. The drive chain 116 passes over a larger sprocket 118which is nonrotatably connected to a second shaft 120. One end of theshaft 120 is connected to another small sprocket 122 which drives achain 124 connected to a cam shaft sprocket 126. The cam shaft 128drives an eccentrically mounted circular cam disk 130 having a smoothperipheral surface 131 which rides on the linear operator of the controlvalve 112. A tab 133 is mounted on the cam 130 for operating a limitswitch, as will be discussed.

The other end of the shaft is nonrotatably connected to another smallsprocket 132. The central portion of the shaft 120 nonrotatably mounts aforked charge loading can drive sprocket 134 so that the sprocket 134rotates with the shaft. The forked loading cart drive sprocket 134drivingly engages a loading cart drive chain 136 for driving the forkedloading cart 42 as will be discussed. A pair of transversely extendinglugs 138 are mounted on the forked loading cart drive chain 136 as bestshown in FIG. 5.

The small sprocket 132 on the other end of the shaft 120 is connected bymeans of a side guide plate secondary drive chain 140 to a larger sideguide plate speed reducing sprocket 142 which in turn is nonrotatablyconnected to a side guide plate drive shaft 144. The shaft 144 carries apair of side guide plate drive sprockets 146 and 148. The drivesprockets 146 and 148 each engage the same type of tension drivemechanism for the side guide plates 58 so that only one of thesemechanisms will be discussed. Referring to sprocket 146 it will be seenthat this sprocket drivingly engages a side guide plate primary lineardrive chain 150. The linear drive chain 150 has one of its endsconnected to a tension wire cable 152 by means of a turnbuckle 154 whichenables the tension to be varied in the wire cable 152. The other of itsends is connected to the cable 152 by means ofa U-shaped bracket 156which is fixedly connected to both the chain 150 and the cable 152 bymeans such as bolting, welding, etc. The chain 150 also passes over anidler roller 151 on the stationary shaft 66 as shown in FIG. 4. Thecable 152 also passes over a pulley idler roller 158 which may berotatably mounted on the shaft 62 so that rollers 151 and 158 are insubstantially horizontal alignment. The U- shaped brackets 156 are eachfixed to one of the side plates 58 by welding or bolting so that whenthe drive chains 150 and consequently the brackets 156 move in responseto operation of the motor 110 the drive chains 150 will horizontallydrive the side guide plates 58 either toward the furnace 10 or towardthe unloading platform 16. Due to the sprocket gear ratios of thevarious sprockets in the system, however, the side guide plates 58 ofthe alignment frame are driven much slower than the forked loading cart42. Any desired drive speed ratio can be used. About a 3 to 1 ratio hasbeen found to be satisfactory.

Referring again to FIG. 1 it will be seen that the transfer mechanism 40in the quench chamber 12 is mounted on a hydraulic piston assembly forvertical movement into and out of a liquid quench media 172 in the lowerportion of the quench chamber 12. The piston assembly 170 is moreclearly shown in FIGS. 8 and 9. It can be seen that the assemblyincludes a main piston 172 having a cylindrical piston rod 174 whichextends downwardly into the quench chamber so that in its extendedposition, shown in phantom lines, the A-frame is in the quenching media171 and in its retracted position the A- frame is at the same level asthe unloading platform 16. A pair of auxiliary charge pick up pistons176 and 178 are mounted on opposite sides of the main piston 172 andhave pusher members 180 and 182 at the lower ends of the piston rods.The pusher members 180 and 182 have flat lower surfaces for contactingthe upper surface 49 of the A-frame. The auxiliary charge pick uppistons 176 and 178 only extend a small distance sufficient to lower theA-frame into position for entrance into the furnace chamber beneath thecharge so that the forklift members 90, 92 and 94 are intermediate thehearth members 22. The pistons 176 and 178 override the upwardretracting action of the main piston 172 and in this fashion control thevertical spacing of the transfer mechanism below the charge as it entersthe furnace chamber.

A pair of adjustable stop members 184 and 186 are mounted at oppositeends of the upper surface 49 of the A- frame so as to prevent theA-frame from canting when the main piston 172 is in its retractedposition and the A-frame 41 is out of the quench media.

With reference to FIGS. 3, 4, 5, 6 and 7, the operation of the transfermechanism will now be discussed. With pistons 176 and 178 fullyextended, the motor 110 is activated to drive the prongs 90, 92 and 94of the forked loading cart 42 into the furnace chamber by driving thesprocket 114 counterclockwise causing a counterclockwise movement of thechain 116. This drives the sprocket 1 18 and the drive shaft 120 in acounterclockwise direction. Counterclockwise rotation of the shaft 120similarly rotates the forked loading cart drive sprocket 134counterclockwise thereby causing the loading cart drive chain 136 tomove counterclockwise so that the lugs 138 which extend transverselyfrom each side of the drive chain 136 move toward the left hand end ofthe system as shown in FIG. 5. These lugs engage the downwardly andtransversely extending fingers 101 and brackets 103 mounted on thetransverse support plate 100 of the forked charge loading cart 42. Thelugs 138 engage a shoulder 139 on the brackets 103 and drive the emptycart in a forward direction toward the position in the furnace chambershown in FIG. 7. As shown in FIGS. 3 and 10 the bracket 103 is bolted toboth transverse supports 98 and 100.

At the same time, the sprocket 132 rotates counterclockwise with theshaft 120 driving the chain 140 and the sprocket 142 counterclockwisebut at a much slower rate due to the gear ratio between the sprockets132 and 142. The rotation of the sprocket 142 additionally causes acounterclockwise rotation of the shaft 144 and the side guide platedrive sprockets 146 and 148. Rotation of these sprockets drives thechain 150 and, concomitantly, through the brackets 156 synchronouslydrives the side guide plates 58 to the left as shown in FIGS. 6 and 7toward the furnace chamber 10 but at a much slower speed than that withwhich the forked loading cart 42 is driven. The forked loading cart 42and the side guide plates 58 of the alignment frame 43 are shown intheir fully extended charge pick up position in FIG. 7. Only the prongs90, 92 and 94 of the loading cart 42 enter the furnace chamber 10,thereby reducing the possibility of contamination.

At the same time the sprocket 122 on the shaft 120 through chain 124drives the sprocket 126 and the cam 130 so that when the loading carthas reached a predetermined position in the insulated furnace chamberthe cam 130 through tab 133 may trip a limit switch causing the motor110 to stop (the position of the forked loading cart may also becontrolled by manual control of motor 110). The forks of the loadingcart 42 at this time are positioned beneath the charge in the furnacechamber 10.

The pistons 176 and 178 are at this time returned to their retractedposition as shown in FIG. 9 causing the forks 90, 92 and 94 to lift thecharge off the hearth. The motor 110 is then reversed, the respectivedrive chains, sprockets and shafts are all driven in the oppositedirection causing the lugs 138 to engage the fingers 103 and return theforked loading cart 42 from the furnace chamber into the quench chamber12. The side guide plates 58 are also returned from their positionadjacent the furnace chamber (see FIG. 7) into the quench chamber butagain at a much slower speed. During return of the forked loading cart41 and the alignment frame 43 from the pick up position to the quenchchamber, however, the peripheral surface 131 of the eccentricallymounted cam 130 first rides out of contact with the motor control 112,.causing acceleration of the motor, then after a short period out ofcontact, depresses the motor speed control valve 112 as the cam rotatesclockwise (FIG. 5 so that the motor decelerates as the forked loadingcart 42 and the alignment frame 43 return into the quench chamber 12.This controlled acceleration, fixed speed operation and controlleddeceleration of the transfer mechanism prevents distortion of the chargeand damage to the charge due to jerking movement of the transfermechanism which might otherwise occur.

While the horizontally translatable loading cart 42 and alignment frame43 are operated by the motor 110 a synchronized vertical movement of theA-frame itself must be accomplished to enable the transfer mechanism toenter the furnace, lift the charge off the furnace hearth and return thecharge to the quench chamber and then lower the charge into thequenching media. This is accomplished as discussed with reference toFIGS. 8 and 9 by means of the main piston 172 and the auxiliary chargepick up pistons 176 and 178. lmmediately prior to the time the forkedloading cart 42 is to enter the furnace chamber 10 the pistons 176 and178 are extended, as shown in FIG. 9, to lower the A-frame 41 by about 2inches so that the straight cylindrical forklift members -94 can justpass under the load sitting on the hearth pallet members 22.

As shown in FIG. 6, there are four hearth members 22 and the threeforklift members 90, 92 and 94 are spaced to fit intermediate the hearthpallets. When these forklift members are lowered by action of thepistons 176 and 178 they can enter the furnace chamber intermediate thehearth pallets 22 and be raised to pick up the charge. The forkedloading cart can then be returned without touching the hearth on slidingthe charge across the hearth pallets 22.

Once the forked loading cart 42 is returned to its home" position withinthe A-frame 43, the main piston 172 is fully extended so that theA-frame 43, the forked loading cart 42, the alignment and unloadingframe 41 and the charge are all quenched in the quench bath 71. The onlyportions of the transfer mechanism actually in the furnace, however,were the cylindrical forklift members 90, 92 and 94.

It has been found that this system can be automatically preprogrammedwith conventional circuitry and limit switches to perform the necessaryfunctions or the various functions can be manually controlled by the useof conventional hydraulic and electrical switchingv It has been foundthat the total time for movement of the forklift loading cart 42 intothe furnace chamber, picking up the charge, returning it to the quenchchamber, closing the furnace exit door 26 and vertically descending intothe quench media can be maintained at about 5 seconds with littledifficulty with the apparatus of this invention.

After the quench has been completed the piston 170 is again activated toreturn the rod 174 to its retracted position. In this position theforked loading cart 42 is substantially coplanar with the unloadingplatform 16 shown in FIG. 17 The unloading platform 16 is provided witha separately operable motor 190 which drives an unloading drive chain192, as shown in FIG. I, by means of a sprocket and drive shaftarrangement similar to that of the loading cart 42. To accomplishunloading the exit door 194 from the quenching chamber is opened and themotor 112 is reversed so that the sprocket 118 is driven clockwise (FIG.5). This causes the lugs 138 to pass beneath the depending fingers 101on the transverse support plate (see FIGS. 10 and 12) therebydisengaging the forked loading cart 42 from its drive chain 136. Theside guide plates 58 of the alignment frame 43, however, are stillengaged (see FIG. 5) through the drive shaft 120, the sprocket 132, thedrive chain 140, the sprocket 142 and the drive shaft 144 so that theside guide plate drive chains and the tension cables 1S2 advance theside plates 58 to the right as shown in FIG. 12 toward the unloadingplatform 16.

Referring to FIG. 11, the rails 59 on the side plates 58 of thealignment and unloading frame 43 are each provided with axiallyextending conical indentations 204. Similarly a pair of cylindricalaxially extending alignment rails 206 are provided on the unloadingplatform 16 (see also FIG. 6). Each of the unloading platform rails 206is provided with an axially extending conical end portion 208 which isadapted to mate with the conical indentation 204 on the side guide platerails 59 of the alignment frame 43. As the side guide plates 58 areadvanced toward the unloading platform 16 positive alignment is obtainedby alignment of the end portions 204 and 208. The side guide plates 58by means of rollers 106 and rails 59 (see FIG. 4) guide the forkedloading cart 42 toward the unloading platform 16. The depending fingers101 on the forked loading platform are transferred to a position wherethey depend on each side of the platform unloading drive chain 192. Atthe same time the motor on the unloading platform 16 is energized tocause a clockwise rotation of the drive chain 192. Drive chain 192 isalso provided with a pair of transversely extending lugs 210, best shownin FIGS. 6, 11 and 12, which engage with the depending fingers 101 onthe forked loading cart transverse support plate 100. The drive chain192 thus continues movement of the loading cart 42 off the A-framestructure 41 and onto the unloading platform 16. The rollers 106 moveout of engagement with the rails 59 and into operative engagement withthe unloading platform rails 186 as the loading cart moves fully ontothe platform 16. The charge is now in position to be removed from theforked loading cart 42 and the forklift members 90, 92 and 94 can bewiped clean before being returned into the quench chamber 12 and intothe furnace chamber to retrieve the next heat treated charge.

There are several advantages to using a forked loading cart such as usedherein. For example each of the prongs or cylindrical lift members onthe fork can easily be wiped clean ofthe quench media so that thesemembers do not carry a corrosive or contaminant surface coating which istransferred into the furnace chamber during charge pick up. The door 26is closed immediately after the charge is removed and the refractoryplug 27 is extended into radiation tight relationship with the furnacechamber. Thus the furnace chamber can be backfilled immediately with thedesired gaseous atmosphere and cooled so that the charge receiving doorcan be opened to receive the next charge. Closing of the door 26 alsoprevents splashing of the quenching media into the furnace chamber.

After the forked loading cart has been wiped clean the motor 190 on theunloading platform 16 is reversed causing the drive chain 192 to drivethe loading cart 42 back onto the side guide plates 58. Alignment of theforked loading cart with the drive chain of the unloading platform isassured by means of the positive alignment of the rails 59 on the sideplates 58 and the rails 206 on the unloading platform 16.

The overall operation of the integral quench furnace of this inventionand the transfer mechanism can perhaps better be described by discussinga time sequence of functions being performed during transfer andunloading, as shown generally in FIG. 13. Again these functions may bemanually or automatically controlled. For example, conventionalcircuitry may be actuated by a series of limit switches which arelocated physically within the furnace and which are closed by theposition of the various members of the transfer mechanism and thefurnace or manual controls may be provided for mechanicallyaccomplishing each of the various functions by operating the appropriatedrive motor or actuator for the element being driven. The first step inheat treatment with the furnace of this invention is to load the chargeon the forked front end loader 14 shown in FIG. 1. The charge is placedon the refractory hearth members 22 by opening the front door 24 andactuating the motor for the loader 14 to raise the loader and advancethe loader on its tracks into the furnace chamber. The loader is thenlowered to place the charge on the refractory hearth members 22 and theloader 14 is retracted. The door 24 is closed. This completes the chargeloading step 1. If an atmosphere is to be used the appropriateatmosphere can be directed into the furnace through a conventional inlet(not shown). After the proper condition either atmosphere or vacuum hasbeen attained in the furnace chamber and the treating temperature hasbeen reached, the charge is maintained in the furnace chamber 10 for thenecessary length of time for the desired heat treatment.

As shown in FIG. 13 step 2, after the heat treatment has been completedsince the quench chamber is evacuated to the partial pressure of thequench media, the furnace is backfilled to compensate for the pressurein the quench chamber 12 and the quench agitator starts agitation of thequenching media. The A-frarne assembly 41 is then lowered to the chargeretrieval position by extension of the pistons 176 and 178 to theirfully extended positions in the upper portion of the quench chamber.Activation of pistons 176 and 178 lowers the A-frame by approximately 2inches so that the lift members 90, 92 and 94 can pass beneath thecharge in the furnace chamber intermediate the hearth pallets 22.

In step 3, which may be manually controlled or activated by a steppingswitch, the insulated door 27 intermediate the quench chamber and thefurnace chamber is retracted into the intermediate solid door 26 bymeans of the hydraulic actuator 30 which may be manually controlledthrough an appropriate hydraulic circuit or automatically activated. Theintermediate door 26 with the insulated door 27 retracted therein isthen lifted to approximately a half open position as best shown in FIG.7. When the door is in the half open position, step 4 is performed. Theforked loading cart 42 is activated. as explained, to enter the furnacechamber, as shown in FIG. 7, the pistons 176 and 178 are fully retractedand the door 26 is fully opened. In step 5, the forked loading cart iswithdrawn into the quench chamber 12, as shown in FIG. 2, with the heattreated charge thereon. The loading cart undergoes controlledacceleration and then deceleration in this step due to cam 130, asexplained.

In step 6 the door 26 is closed. Next, in step 7, the piston 172 isactivated to its fully extended position so that the transfer mechanismand charge are immersed in the quenching media 71 as shown by the dashedlines of FIGS. 1, 2 and 8. The charge is maintained in the quench mediafor the desired time. During the quench, the furnace may be backfilled,cooled and reloaded with the next charge.

In the eighth step, the piston 172 is returned to its fully retractedposition raising the A-frame 41 and the charge from the quenching media.In step 9, the quench chamber is returned to atmospheric pressure and instep 10 the unloading door 194 is opened to atmosphere. Step 11 is theactivation of the motor in the unload direction to align the forkedloading cart 42 for egress onto the unloading platform 16. In step 12the unloading platform motor is activated to drive the cart 42 onto theunloading platform. The forklift members 90, 92 and 94 of the loadingcart 42 can then be wiped clean before step 14 in which the motor 190returns the forked loading cart 42 back into position adjacent theA-frame 41. In step 15, the lugs 138 of the drive chain 136 are drivencounterclockwise to engage the depending shoulders 139 on brackets 103and return the cart 42 onto the A-frame 41. The mechanism and furnaceare now ready for the next heat treatment to be completed so that thequench cycle can begin.

As can be seen from FIG. 13 the operation of the furnace and transfermechanism can be easily automated through conventional circuitry using amain stepping switch controlled by function or time operated limitswitches. The functionally operated limit switches in conventionalmanner may be placed conveniently within the apparatus for tripping byits moving parts.

Among the many advantages of the integral quench furnace mechanisms ofthis invention is that mechanical rotary or linear seals which face theatmosphere are eliminated by the use of hydraulic drive motors andactuators throughout the system. This prevents the possibility of airleaking into the system through worn seals. The hydraulic fluidsgenerally are compatible with the quenching media so that worn seals donot ruin the charge being treated but yet can be easily de tected.

What is claimed is:

1. A metallurgical furnace having a quench chamber and an elevatedtemperature heat treating chamber comprising:

means for dividing said quench chamber from said heat treating chamber;and

transfer means in said quench chamber for entering said heat treatingchamber at the completion of the heat treating cycle, lifting the chargevertically and transferring the charge being heat treated into aquenching media in said quench chamber without sliding and rolling saidcharge, said transfer means being maintained outside said heat treatingchamber until time for quenching said charge, said transfer meanscomprises vertically translatable means mounted for movement within saidquench chamber and horizontally translatable means mounted forhorizontal translation from within said vertically translatable means.

2. A furnace as defined in claim 1 wherein said vertically translatablemeans is an A-frame support member.

3. A furnace as defined in claim 1 wherein said horizontallytranslatable means includes a forked loading cart mounted so that onlythe fork prongs enter said heat treating chamber.

4. A furnace as defined in claim 1 wherein said horizontallytranslatable means comprises an alignment frame mounted for horizontaltranslation from within said vertically translatable member and aloading cart mounted for horizontal translation from within saidalignment frame, said furnace further including drive means operativelyconnected to said vertically and horizontally translatable means.

5. A furnace as defined in claim 4 wherein said alignment framecomprises:

a pair of spaced guide plates;

a pair of longitudinally extending guide rails attached to the opposinginner surfaces of each of said guide plates; and

said loading cart comprises:

a plurality of axially extending cylindrical members;

a plurality of transverse support members spacedly mounting saidcylindrical members, a pair of loading cart side plates, and a pluralityof spaced roller pairs mounted on the outer surfaces of said loadingcart side plates for movably mounting said loading cart on said guiderails.

6. A furnace as defined in claim 1 further including hydraulicallyactuated drive means for said vertically translatable member and forsaid horizontally translatable member, said hydraulic drive means havingno seals which interface with the atmosphere.

7. A furnace as defined in claim 6 wherein said drive means comprise:

a hydraulic motor;

a chain and sprocket drive system connected to said horizontallytranslatable member for driving said member in a forward and reversedirection; and

a hydraulic piston attached to said vertically translatable member forvertically driving said vertically translatable member.

8. A furnace as defined in claim 7 wherein said drive means furthercomprise a pair of overriding auxiliary pistons mounted in said quenchchamber for lowering said vertical translatable member by a sufficientdistance to permit at least a portion of said horizontally translatablemember to enter said heat treating chamber beneath the charge being heattreated, said auxiliary pistons being selectively actuatable tovertically translate said vertically translatable member so that saidhorizontally translatable member picks up said charge.

9. A furnace as defined in claim 7 further including means foraccelerating and then decelerating said horizontally translatable memberin a predetermined manner when it is driven from said heat treatingchamber to said quench chamber.

10. A furnace as defined in claim 9 wherein said accelerating anddecelerating means comprises a hydraulic control valve for varying thespeed of said hydraulic motor.

11. A furnace as defined in claim 10 wherein said accelerating anddecelerating means further comprises a cam member operatively connectedto said chain and sprocket drive system for controlling acceleration anddeceleration of said horizontally translatable member.

12. In a metallurgical furnace having a heat treating chamber and ahorizontally adjacent quench chamber, a transfer mechanism comprising:

a vertically displaceable support member mounted within said quenchchamber;

a drive assembly connected to said support member and to a wall of saidquench chamber for moving said support member into a charge pick upposition, a quench position and an unload position;

an alignment frame mounted within said support member for horizontalmovement from within said support member;

a loading cart mounted within said alignment frame for horizontalmovement between a charge pick up position,

a quench position and a charge unload position, said support member andsaid loading cart positions determining the vertical and horizontalpositions of said loading cart during charge pick up, quench and unload;

means for driving said loading cart to said positions; and

means for driving said alignment frame.

13. A transfer mechanism as defined in claim 12 wherein said alignmentframe comprises:

a pair of spaced guide plates, a pair of longitudinally extending guiderails attached to the opposing surfaces of said guide plates, and meansfor attaching said alignment frame drive means to said alignment frame;and said loading can comprises longitudinally extending side mem bers,means on said side members for riding on said guide rails,longitudinally extending charge pick up members for extending into saidheat treating chamber and lifting said charge, and

means for connecting said loading cart drive means to said loading cart.

14. A transfer mechanism as defined in claim 13 wherein said loadingcart has drive engaging members depending therefrom and said loadingcart drive means comprises a motor driven chain having transverselyextending members thereon for engaging said depending members to drivesaid loading cart into said charge pick up position and return saidloading cart to said quench position.

15. A transfer mechanism as defined in claim 14 further including anunloading platform positioned adjacent said quench chamber and means onsaid unloading platform for moving said loading cart into the unloadposition.

16. A transfer mechanism as defined in claim 15 wherein said means onsaid unloading platform comprises:

a motor, an unload drive chain operatively connected to said motor andmembers on said chain for engaging said depending members to drive saidloading cart into said unload position after said alignment frame hasbeen driven toward said unload position.

17. A transfer mechanism as defined in claim 16 wherein said unloadingplatform further comprises means for aligning with said alignment framewhen said alignment frame is driven toward said unloading platform.

18. A transfer mechanism as defined in claim 12 wherein said loadingcart and alignment frame driving means comprise a motor driven chain andsprocket arrangement wherein said loading cart is driven at a fasterrate toward said charge pick up position and quench position.

19. A transfer mechanism as defined in claim 18 further including meansfor disengaging said loading cart from its drive means after saidloading cart is driven toward said unloading platform and means on saidunloading platform for driving said loading cart thereon after saidalignment frame has positioned said loading cart.

20. A metallurgical furnace having a quench chamber and a heat treatingchamber and a transfer mechanism comprising:

a horizontally translatable loading cart;

a horizontally translatable alignment frame for mounting said loadingcart;

means for vertically lifting said loading cart when said cart is placedbeneath a load; and

means for driving said loading cart and said alignment frame atdifferent speeds.

21. A transfer mechanism as defined in claim 20 wherein said drivingmeans comprises:

a drive chain mounted over said first sprocket for engaging saidsprocket and said loading cart for driving said load mg cart;

a pair of second sprockets attached to said shaft; and

1. A metallurgical furnace having a quench chamber and an elevatedtemperature heat treating chamber comprising: means for dividing saidquench chamber from said heat treating chamber; and transfer means insaid quench chamber for entering said heat treating chamber at thecompletion of the heat treating cycle, lifting the charge vertically andtransferring the charge being heat treated into a quenching media insaid quench chamber without sliding and rolling said charge, saidtransfer means being maintained outside said heat treating chamber untiltime for quenching said charge, said transfer means comprises verticallytranslatable means mounted for movement within said quench chamber andhorizontally translatable means mounted for horizontal translation fromwithin said vertically translatable means.
 2. A furnace as defined inclaim 1 wherein said vertically translatable means is an A-frame supportmember.
 3. A furnace as defined in claim 1 wherein said horizontallytranslatable means includes a forked loading cart mounted so that onlythe fork prongs enter said heat treating chamber.
 4. A furnace asdefined in claim 1 wherein said horizontally translatable meanscomprises an alignment frame mounted for horizontal translation fromwithin said vertically translatable member and a loading cart mounTedfor horizontal translation from within said alignment frame, saidfurnace further including drive means operatively connected to saidvertically and horizontally translatable means.
 5. A furnace as definedin claim 4 wherein said alignment frame comprises: a pair of spacedguide plates; a pair of longitudinally extending guide rails attached tothe opposing inner surfaces of each of said guide plates; and saidloading cart comprises: a plurality of axially extending cylindricalmembers; a plurality of transverse support members spacedly mountingsaid cylindrical members, a pair of loading cart side plates, and aplurality of spaced roller pairs mounted on the outer surfaces of saidloading cart side plates for movably mounting said loading cart on saidguide rails.
 6. A furnace as defined in claim 1 further includinghydraulically actuated drive means for said vertically translatablemember and for said horizontally translatable member, said hydraulicdrive means having no seals which interface with the atmosphere.
 7. Afurnace as defined in claim 6 wherein said drive means comprise: ahydraulic motor; a chain and sprocket drive system connected to saidhorizontally translatable member for driving said member in a forwardand reverse direction; and a hydraulic piston attached to saidvertically translatable member for vertically driving said verticallytranslatable member.
 8. A furnace as defined in claim 7 wherein saiddrive means further comprise a pair of overriding auxiliary pistonsmounted in said quench chamber for lowering said vertical translatablemember by a sufficient distance to permit at least a portion of saidhorizontally translatable member to enter said heat treating chamberbeneath the charge being heat treated, said auxiliary pistons beingselectively actuatable to vertically translate said verticallytranslatable member so that said horizontally translatable member picksup said charge.
 9. A furnace as defined in claim 7 further includingmeans for accelerating and then decelerating said horizontallytranslatable member in a predetermined manner when it is driven fromsaid heat treating chamber to said quench chamber.
 10. A furnace asdefined in claim 9 wherein said accelerating and decelerating meanscomprises a hydraulic control valve for varying the speed of saidhydraulic motor.
 11. A furnace as defined in claim 10 wherein saidaccelerating and decelerating means further comprises a cam memberoperatively connected to said chain and sprocket drive system forcontrolling acceleration and deceleration of said horizontallytranslatable member.
 12. In a metallurgical furnace having a heattreating chamber and a horizontally adjacent quench chamber, a transfermechanism comprising: a vertically displaceable support member mountedwithin said quench chamber; a drive assembly connected to said supportmember and to a wall of said quench chamber for moving said supportmember into a charge pick up position, a quench position and an unloadposition; an alignment frame mounted within said support member forhorizontal movement from within said support member; a loading cartmounted within said alignment frame for horizontal movement between acharge pick up position, a quench position and a charge unload position,said support member and said loading cart positions determining thevertical and horizontal positions of said loading cart during chargepick up, quench and unload; means for driving said loading cart to saidpositions; and means for driving said alignment frame.
 13. A transfermechanism as defined in claim 12 wherein said alignment frame comprises:a pair of spaced guide plates, a pair of longitudinally extending guiderails attached to the opposing surfaces of said guide plates, and meansfor attaching said alignment frame drive means to said alignment frame;and said loading cart comprises longitudinally extending side members,means on Said side members for riding on said guide rails,longitudinally extending charge pick up members for extending into saidheat treating chamber and lifting said charge, and means for connectingsaid loading cart drive means to said loading cart.
 14. A transfermechanism as defined in claim 13 wherein said loading cart has driveengaging members depending therefrom and said loading cart drive meanscomprises a motor driven chain having transversely extending membersthereon for engaging said depending members to drive said loading cartinto said charge pick up position and return said loading cart to saidquench position.
 15. A transfer mechanism as defined in claim 14 furtherincluding an unloading platform positioned adjacent said quench chamberand means on said unloading platform for moving said loading cart intothe unload position.
 16. A transfer mechanism as defined in claim 15wherein said means on said unloading platform comprises: a motor, anunload drive chain operatively connected to said motor and members onsaid chain for engaging said depending members to drive said loadingcart into said unload position after said alignment frame has beendriven toward said unload position.
 17. A transfer mechanism as definedin claim 16 wherein said unloading platform further comprises means foraligning with said alignment frame when said alignment frame is driventoward said unloading platform.
 18. A transfer mechanism as defined inclaim 12 wherein said loading cart and alignment frame driving meanscomprise a motor driven chain and sprocket arrangement wherein saidloading cart is driven at a faster rate toward said charge pick upposition and quench position.
 19. A transfer mechanism as defined inclaim 18 further including means for disengaging said loading cart fromits drive means after said loading cart is driven toward said unloadingplatform and means on said unloading platform for driving said loadingcart thereon after said alignment frame has positioned said loadingcart.
 20. A metallurgical furnace having a quench chamber and a heattreating chamber and a transfer mechanism comprising: a horizontallytranslatable loading cart; a horizontally translatable alignment framefor mounting said loading cart; means for vertically lifting saidloading cart when said cart is placed beneath a load; and means fordriving said loading cart and said alignment frame at different speeds.21. A transfer mechanism as defined in claim 20 wherein said drivingmeans comprises: a motor; a shaft operatively connected to said motorfor rotation therein; a first sprocket connected to said shaft forrotation therewith; a drive chain mounted over said first sprocket forengaging said sprocket and said loading cart for driving said loadingcart; a pair of second sprockets attached to said shaft; and a pair ofsecond drive chains connected to said second sprockets and to saidalignment frame for translating said alignment frame.
 22. A transfermechanism as defined in claim 21 wherein said first sprocket is largerthan said second sprockets so that said loading cart is translated at afaster rate than said guide rails.